Crystal (1987) suggests that code switching occurs when individual who is bilingualism alternates between two languages during his/her speech with another bilingual person.

There are kinds of code switching as suggested by some sociolinguists:Blom and Gumperz (1972):Situational Code Switching

It occurs when the language change according to the situational in which the conversations find themselves; It can be found in the use of speech level in languages which have speeches levels. Each of the levels has its social function and is used in certain interlocutors. For instance, a young speaker will use the upper (very formal) level of the language to and older listener in kind of situation; and he will use the lower (intimate) level to communicate of the person with same age.

Metaphorical Code Switching

It has an affective dimension to it: the choice of code carries symbolic meaning, that is, the language fits the message. This is illustrated in a quote attributed to Charles V, the Holy Roman Emperor, which indicates attitudes about certain languages being holy, the language of love or male solidarity, or crude or bestial: ‘I speak Spanish to God, Italian to women, French to men, and German to my horse.’

Hoffman (1991):

Tag switching (Emblematic)

With tag switching, it is the insertion of a tag phrase from one language into an utterance from another language which constitutes a switch, and given the tags are monolingual utterance without syntactic rules, for example: An adult Spanish-American English speaker: “„. . . Oh! Ay! It was embarrassing! It was very nice, though, but I was embarrassed"

Inter-sentential switching (between sentences)

It occurs outside the sentence or the clause level, and often takes place according to turns taken by speakers in a conversation, example an adult Spanish-English bilingual says: “Tenia zapatos blancos, un poco, they were off-white, you know”

Intra-sentential switching

It concerns language alternation that occurs within a sentence or a clause boundary. Sometimes it includes mixing within word boundaries. The switch that occurs within a sentence. It is often occurred when someone uses one language and suddenly switches into another language in a sentence, for example: a French-English bilingual says: “Va chercer Marc (go and fetch March) and bribe him avec un chocolat chaud (with a hot chocolate) with cream on top”